Is it sanitary to wash white towels and dish cloths and underwear?

Whether or not you combine all your white bleachable items with your underwear into one load or separate a few items to wash depends on the condition of the underwear. If there are any fecal solids present then I would consider washing those items separately from kitchen towels and cloth napkins. Otherwise it's perfectly reasonable to combine all your white items into one load. That said here are some other considerations to make sure you are properly disinfecting your laundry:

1. Use 3/4 cup of bleach for a regular size load with an average soil level, and 1 ¼ cup for an extra-large or heavily soiled load.  Using less than the recommended amount will not provide the correct amount of bleach active to disinfect the load.

2.  Don't overload the washer with too much laundry. Items need to circulate or tumble freely through the wash water for optimum cleaning.

3.  Don't overload the washer with items that have excess stain remnants still on the fabric. In that case it's important to increase the amount of bleach to 1 1/4 cup or wash two smaller loads if you must use a bleach dispenser to add bleach to your washer and it limits the amount of bleach you can add.